Disinfecting objects, materials, tissues and even body parts has been the source of study and research for centuries. Disease causing microorganisms flourish all around, but truly begin to wreak havoc when their numbers build around vulnerable populations of the elderly, immuno-compromised or the very young. In an attempt to address this danger, the Centers for Disease Control and Prevention (“CDC”) produces an annual study describing various methods of sterilization and disinfection, and under what circumstances each method is appropriate. It is commonly recognized that to sterilize an object is to rid the object of essentially all live microorganisms. To disinfect an object is to rid the object of a percentage of live microorganisms. Described methods by the CDC to achieve sterilization, and even disinfection, include harsh chemicals, glass bead sterilizers, autoclaves and vaporized hydrogen peroxide. A constant struggle exists to achieve the highest level of microorganism eradication, while preserving the viability and characteristics of the underlying object, tissue or matter; using the least amount of energy, and having the least environmental impact.
Although the necessity for sterilization and disinfection encompasses virtually all industries, certain environments such as hospitals, nursing homes, daycares, schools and medical clinics are at especially high risk for microorganism spread and cross contamination. Professionals and scientists continually seek more effective, less expensive and more environmentally friendly ways to destroy or inactivate unwanted bacteria, molds, fungi and viruses.
Hospital and nursing home spread of destructive germs like the well-known Staphylococcus aureus cause significant cost, discomfort and extended suffering for patients already coping with underlying illness or disability. Patients affected by Staph aureus require expensive antibiotics, sometimes suffering additional side effects in the process. The growing migration of Staph aureus in recent years, followed by aggressive antibiotic treatment, has caused antibiotic resistant strains to evolve. One such strain, Methicillin resistant Staphylococcus aureus (“MRSA”) is a bacterium that is resistant to a large group of antibiotics called the beta-lactams. This group includes the penicillins and cephalosporins. For patients with MRSA, physicians must often resort to treatment with Vancomycin, an extremely expensive and potent antibiotic. New “superbugs” have begun to emerge that, frighteningly, are resistant even to powerful Vancomycin. One such bug is known as Vancomycin Resistant Enterococcus or (“VRE”). The cost associated with fighting these “superbugs” and the toll on human life is mounting.
In 2007, the CDC estimated that the number of MRSA cases in hospitals doubled nationwide, from approximately 127,000 in 1999 to 278,000 in 2005. (Klein and Laxminarayan, 2007). They further estimated that annual deaths increased from 11,000 to more than 17,000. The preference is to prevent the contamination and cross contamination of harmful microbes, rather than attempt ever more aggressive means to treat patients affected by them. In that quest, hospitals have launched targeted campaigns to reduce the spread of all nosocomial infections, including MRSA and VRE. One obvious source of contamination is that of bed linens, washcloths and towels. Such items come into contact with copious amounts of bodily fluids and are exceedingly difficult and costly to fully disinfect. Current methods to sterilize hospital linens, such as steam or harsh chemicals, are expensive highly consumptive of energy and can be destructive to the fibers, shortening the lifespan of the linens.
Medical environments incorporate various levels of cleanliness depending on the object being cleaned. Sterilization is indicated for medical instruments or devices that enter the sterile tissues, the vascular system or where blood flows. As sterilization almost completely eradicates microorganisms, it has become the preferred method for cleaning objects that will be used invasively. (Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008, CDC; Rutala and Weber). Disinfection is a less potent technique than sterilization and may be high level, mid level or low level, depending on the desired use of the object, its level of intended invasiveness and the corresponding potential for contamination in the human body.
Although sterilization can be achieved by use of harsh chemicals, irradiation, steam and other methods, certain disadvantages including high cost, high energy requirements, high intensity of time and labor and harmful chemical environmental effects may accompany each of these.
Our society is increasingly becoming a “throw-away” society. Part of the reason modern day services, and specifically medical services, are so expensive is due to this disposability factor. A vast number of small articles are used in daily treatments and thrown away due to concerns about the ability to thoroughly sanitize. A cost-effective way to safely and consistently sanitize these objects is needed.
Another cause for concern with regard to potentially harmful microorganisms is our food supply. A common theme in the news is the contamination of large scale crops by common pathogens such as Salmonella sp or Eschericia Coli sp. Often growers are forced to recall and dispose of contaminated crops, at a huge cost and societal waste. Decontamination would be a welcome alternative.
Contamination is not limited to human food supplies. Pet foods are often contaminated with microorganisms which can easily be transmitted to a human handling the food or accidentally ingesting it.
United States Patent Application 2009/0092708 previously discussed a method for using microwave radiation to extend the shelf-life of foods, however, the inventors therein utilized a continuous stream of microwave radiation lasting in duration of at least seven seconds to pretreat foods prior to packaging, far different from the repetitive pulse therapy and other novel method and apparatus disclosed herein.
Microwave radiation is typically thought to be unable to emit radiation waves in an even and consistent enough pattern to allow for reliable sterilization or disinfection. To achieve sterilization requires a 99-100% elimination of microorganisms, heretofore not reliably achievable by microwaves. Microwave radiation was recently suggested for use to sterilize mail of harmful organisms such as anthrax. The United States Postal Service, however, determined that microwave radiation, as currently understood, would be ineffective for mail sanitation, primarily due to its perceived inability to achieve reliable and even application.
A method and system is needed to reliably and efficiently sterilize food and non-food objects, at a reasonable cost, without altering the object's characteristics, further harming the environment or requiring large amounts of energy. Potential applications of such a novel technology run the gamut from ridding locker rooms of athlete's foot to sterilizing hospital linens to reducing microorganism populations in human, pet and stock animal food.